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Northwest Arkansas via Chicago Area via Straight Up from There on Lake Superior

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Top End Dual Fuel Proposals - Look Good?

After weeks of educating myself with much help from this forum, I have narrowed my search to 2 dual fuel heat pump/natural gas furnace proposals. Several were just way out there. I had my local electric co-op independently check the house and it is very efficient and they provided me with cooling and heating sizes. Several of the proposers also ran a Manual J calculation that approximated the co-op calculation.

The house, built in 1994 in extreme Northwest Arkansas, is about 3700 sq ft with a walk out on the lower level, extreme southerly exposure with lots of windows. The existing 80% gas furnace is an 88,000 Btu's and the split (10 SEER?) AC is a builder's model 4-ton. Both seem adequate as the house is tight, insulated, good vinyl windows, additional 6 inches of cellulose in attic on top of probably original 10 inches fiber glass.

I finally asked that neither propose more than 80% furnace although they had to be VS and modulating if possible. Winters here are only 1-2 months and not very serious like the Upper Mid-West gets. Both will seal the return air plenum that concentrates an upper and lower floor return in a plywood plenum exposed to fiber glass insulation before going into updraft furnace.

Really appreciate your input. They look good? Any holes you would fill?

The AHRI # for the Lennox setup would be 1247483. 12.75 EER, 17.50 SEER, 8.60 HSPF. The York setup yields better numbers, 12.75 EER, 18.00 SEER, 10.15 HSPF. Comparable setups, but of course the York has more heating stages. The Lennox ComfortSense 7000 can control humidity, but I can't make out the York thermostat part number to find more info on it. Perhaps you can clarify that with the dealer. I know York has a VisionPRO 8000 thermostat with a part number for it, but it's not the IAQ (unless they have another one for the IAQ). The York setup includes IAQ accessories. I would at least look into a pleated media filter with the Lennox setup. You may get a bigger rebate.

On the Lennox unit, I think it needs a aftermarket Aspen coil to make a match that meets the federal tax credit limits.

I agree with you on the 80% furnace. Trane finally came out with a communicating 80% V furnace for that market. There is no payback, unless you have a very large home, on the condensing furnaces from about Northern Missouri on south. Especially with a dual fuel set-up.

Although, I do like the ideal of having sealed combustion. My furnace is installed in the basement, so when it's running, I have increase infiltration. Same with my hot water heater and clothes dryer.

Northwest Arkansas via Chicago Area via Straight Up from There on Lake Superior

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Ryan, thank you for the quick response. Wading through all of those extra characters in the coil listings must take practice. I have already sent an email to the York contractor asking for a better thermostat designation.

Maybe you can help me with why does the York have better numbers but I believe that AHRI says the Lennox is cheaper to heat and cool in the fields under "Est. National Avg. Annual Operating Costs". Are those numbers nonsense? I have seen similar unbelievable costs for other units with high costs but great numbers?

motoguy, regarding having "sealed combustion" I lived for years with furnaces either in the laundry room or the basement. Fortunately, this unit is in a large garage so hopefully no combustion fumes will penetrate the house.

The York contractor, listed as a commercial HVAC guy on the York site, told me that the ASPEN coil is 24" wide versus 21" for the furnace and that he would center and match it up. Are both of you comfortable with going with the large ASPEN coils and the numbers they seem to carry?

I don't pay any mind to the estimated national averages. The installers shouldn't just put a wider coil on top of a furnace without making a proper transition/following installation instructions (don't want to bypass any coil surface area, lowering efficiency). I checked the Aspen coil spec sheets, but couldn't determine for certain whether they had a coil matching your width. I would ask your dealer if there is a matching-width coil. The Lennox furnace is 21", and that dealer is proposing a CE60D44 coil. Perhaps that's what should be used with the York (?).

Northwest Arkansas via Chicago Area via Straight Up from There on Lake Superior

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Originally Posted by RyanHughes

... The installers shouldn't just put a wider coil on top of a furnace without making a proper transition/following installation instructions (don't want to bypass any coil surface area, lowering efficiency). ...

Very good point. I believe that he said he would transition. This guy is listed as a commercial HVAC contractor so I have more faith that he knows how to customize.

Note too that that coil is a 5-ton on top of a 4-ton unit. The distributor said that this is standard practice since some units capacities are achieved doing this. Sound right?

a follow up Q about dehumidifying options.... Do you know if the York Affinity 18 SEER HP and the York 'stat (which I believe is the Honeywell IAQ; which qualifies for their $$$ rebate) allow this unit to dehumidfy aside from the cooling fxn?

Northwest Arkansas via Chicago Area via Straight Up from There on Lake Superior

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Originally Posted by beenthere

I think you'll find the York stat is he TH8321.
It does cool to dehumidify. but can't slow the blower.

Getting a bit confused after the last question on York thermostat. The $1,700 rebate requires a "matching York programmable thermostat". The rebate is very important to the retired guy as is making this unit operate properly so could you please clarify the following:

- Does the proposed York Thermostat SI-THERM22P7Y 2H/2C 7-day programmable qualify for the rebate?

- If it qualifies, is it inadequate to properly control this heat pump/variable speed furnace ("Cool to dehumidify, and blower control are not a listed features of that stat")?

- Can I still get the rebate by asking the contractor to upgrade to a more capable thermostatAND which one should I ask for?

Northwest Arkansas via Chicago Area via Straight Up from There on Lake Superior

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Originally Posted by beenthere

The above thermostat does qualify. Its a labeled York thermoststat(has "York" name on it).

Its not that its inadequate. Just doesn't make full use of the equipments ability.
Ask him to include the IAQ thermostat.
Means your buying it separately. And end up with 2 thermostats.

Thank you, beenthere. Looks like you suggest the Honeywell VisionPro IAQ Touchscreen 7-Day Programmable Thermostat, Version 2 (TH9421U). Price is not terrible on Amazon but Honeywell's list price is pretty steep - don't know what the contractor will come up with especially if he has never used an IAQ.

This version seems to have an "Equipment Interface Module". Another (TH9421C1004) slightly cheaper version does not seem to have the interface module.

Is it necessary or does it just simplify the wiring to the thermostat?

Do either of these thermostats require an outdoor sensor?

I read in other posts that the IAQ provides "2 stages of gas heat". The York is a modulating furnace from around 50% up to 100%. Does this 2-stage thermostat defeat the modulating furnace feature in any way or just kick the furnace down to stage 1 and it modulates it's way up to 100% on it's own?

If I am going to have to buy 2 thermostats, one to satisfy the rebate and one to control the unit properly, should I just ask the contractor to include the simplest, cheapest York matching thermostat that qualifies for the rebate?
If so what York model would that be?

This novice would appreciate specific models so I can talk to the contractor.

Contractor just emailed me and said he is proposing York s1-tbsu32hp7s and that it does it all, probably a Honeywell. Don't know what that is and cannot find it via Google.
Any thoughts?